This invention relates to a waveguide for laser beams for use in laser-utilizing devices such as laser-utilizing machine tools or laser-utilizing surgical knives.
Laser-utilizing machine tools for cutting, drilling, or fusion-welding metallic and other organic materials by the use of electromagnetic wave energy generated by the electrical excitation of gases such as helium, neon, or carbon dioxide, or a solid such as YAG, have acquired a very important position in the industrial field.
Some of the apparatus employing carbon dioxide lasers will be used in the field of the manufacture and processing of precision toothed wheels. Now in practical use is a CO.sub.2 laser surgical knife, which is appreciated due to its capability of positionally accurate application to the diseased part and its instantaneous hemostatic effect.
This invention relates to a waveguide for light beams which uses spherical surface mirrors and permits arbitrary setting of laser beam diameter.
Usually, a waveguide for a laser beam is obtained by a combination of mirrors and optical lenses. For example, flat mirrors have so far been used in the waveguide for the laser surgical knife. Since laser beams are parallel to each other, the transmission of the beams without a change in the diameter of a plurality of parallel beams would seem to be possible by a combination of flat mirrors and the formation of a waveguide in a shape and size as desired. However, in practice, the diameter of a "bundle" of such laser beams gradually expands due to the angular expansion of the beam. In the case of a carbon dioxide laser, the diameter of a beam bundle may double with a 2 meter advance.
The use of concave mirrors serves to suppress the diametral expansion of the beam bundle. In Japanese Patent Laid-Open No. Sho 55-81644, a waveguide such as above is proposed. This waveguide is composed so as to guide laser beams to a desired position along a desired direction by a combination of concave surface mirrors instead of flat surface ones, and suppress the expansion of beam bundle. In the invention as proposed, however, no particular attention is paid to the relation between the mirror surface and the beam axis.